When composite materials are molded into structures having cavities, such as hat stringers, for example and without limitation, there may be a need for tooling that applies outward pressure from within the cavity during curing, and which can be removed from the cavity after curing. Existing tooling used for this purpose may include, without limitation, inflatable rubber mandrels; solid mandrels such as metal, rubber or composite mandrels; or dissolvable mandrels. Solid rubber or composite mandrel are sometimes preferred for certain applications, however when subjected to heat and pressure, this type of mandrel may produce a cavity having a distorted cross-sectional shape and/or may exert uneven pressure on the composite laminate.
Accordingly, there is a need for a removable mandrel that reduces or eliminates distortion of the cavity shape, and exerts substantially uniform pressure over the composite laminate during curing at elevated temperatures.